/**
 * @param {string} 字符串
 * @param {string} 匹配项
 * @return {number}
 */
var strStr = function (haystack, needle) {
    if (haystack.split(needle)[0] === haystack) {
        return -1;
    } else {
        return haystack.split(needle)[0] === '' ? 0 : haystack.split(needle)[0].length;
    }
};